well u probably first have the cat dig a trench for you to sink the rail into and then after that u can set it in and have the cat fill it over and pack it down. Then basically you shape a lip and thats about it. A good cat driver and it might take about 30mins.
usualy to get it dug in, ground out once more, level, then random stuff, about 3-4 hours. thats here at breck atleast. for an average size rail. the c down c or something like that takes all day though.
i think its all about what kinda rail it is, ive seen the park guys just chuck a rail out into the middle of the hill then pile up some snow pack it down and probably go smoke a joint haha